The News-Herald. [volume] (Hillsboro, Highland Co., Ohio) 1886-1973, 1887-03-31
JOLLIERY EXPLOSIONS.
Efforts Which Have Been Made
to Prevent Them.
The "Davy" Lamp and Fire Damp-Coal
Dust Dangers-"Sh OF Firing" to Give
Place to Safer Methods OF
Explosions.

Explosions.
The atmosphere of every coal-mine
probably contains more or less marsh
gas. although in some the amount is so
very small that the air within them
could never become explosive under Or
dinary conditions of working. There
is no doubt that gas frequently escapes
detection owing to the imperfection of
the means employed for its recognition.
If present in certain proportions the
marsh gas is revealed by the elonga-
ton of the flame of the safety-lamp, or
by the appearance of what is
known as 'cap' upon the flame
An experienced eye can determine pret-
ty accurately the relative amount of
the tire-damp from the size and character
Of the cap upon properly trimmed
flame: but the test altogether fails when
the proportion of gas falls below two
per cent. This amount small as it may
seem, may, under certain circum-
stances, prove highly dangerous. The
mine-manager and the 'fircmen' re-
quire to use some more delicate method
of detecting small quantities of fire.
damp than that usually employed. For
tunately such methods are not unknown.
Mr.. Liveing has devised very ingeni-
Gus Indicator, by which the existence
of marsh gas can be detected and its
amount estimated even when the guam
tity is as low as quarter per cent.
Two precisely similar pieces of thin
platinum wire are simultaneously
heated to bright redness by the action
of a small magneto-electric machine
worked by hand. Ono of the wires is
contained in small tube filled with pure
air; the other can be surrounded at will,
and in minute or two, with air
from any part of the mine. If fire.
damp is present it burns round the hot
wire, which is thereby increased in
temperature and emits more brilliant
light. BY comparing the intensities of
the light emitted by the two wires by
the aid of a very simple photometric
arrangement the percentage amount of
firc-damp present may be at once de-
termined. The apparatus is portable
and easily worked, and is well adapted
for use under ground.
Seventy years have elapsed since Sir
Humphrey Davy invented the safety
lamp which is associated with his name.
1t is almost impossible to overestimate
the influence of that invention in the
development of coal-mining-in the de-
velopment indeed, of our national
prosperity. 1t has unquestionably
saved thousands of lives, and has en-
ablad millions of tons of coal to be
raised which. without it, could not pos
Silly have been won.
1t is related that when Mr.. Buddle,
whose name is well known in the
history Of coal-mining for the
improvements he introduced into
the system of ventilating collieries.
took down one of the first Davy lamps
ipto fiery pit and beheld the fire-damp
'cap" playing round the light and APP
pa,ently imprisoned within the wire-
gauze cylinder, he exclaimed exult-
ir=ly: Eat last we have subducd this
monsterr'
No: year passes. however, without
the monster showing us that he is
still very far from subjection; and,
strange to say, the Davy lamp itself
and the very system of ventilation
which we owe to Mr.. Buddle, as de-
veloped in these later times. have con-
spircd to aid the monster in his work
Of havoc and disaster.
How this has come about may be
told in a very few words. When the
lamp was first introduced the ventilat-
ing currents in mines seldom exceeded
velocity of three hundred feet per
minute in the air-ways, and they were
usually very feeble in the working
places. Nowadays the enormous fans
and other mechanical ventilators which
are employed cause tho air to travel at
velocities approaching two thousand
feet per minute in the air-ways, and cur
rents of more than four hundred feet per
minute are not unfrequently met with
at the working places. Under these
conditions the Davy lamp and, in a
iCecSi NCSiCc, bWo ottcI Wclt-kuOWH
forms of safety lamp--the Clanny and
the Stephenson lamps-beconle abso-
lutely unsafe in an explosive atmos-
phcre. Indeed, the ordinary Davy
lamp willignite gas outside it if ex-
posed TO an explosive current travelling
at less than four hundred feet per min
ute
Tho Royal Commissioners, as far back
as 1880. directed the attention of the
Home Secretary to the fact s.that the
employment of the ordinary Davy lamp
without shield of metal or of glass, in
an explosive mixture. when the air
currents exceed six feet per second, is
attended with risk of accident almost
amounting to certainty" Indeed.
merely attempting to blow out the
dame within the lamp may cause it to
ignite an inflammable mixture. Happily
Invention has not been long behind
aecessity. and there are at least half-a-
dozen forms of lamp which are safe
ansler ciirrsnt velocitiss exceeding three
thousand feet per minute. Everybody
will sgyse With the conclusion Of the